Control circuits and systems for controlling an electrical load, such as an electric motor, and a movable device driven thereby are numerous and varied in their operation. Some such systems may control the operation of the electric motor and/or the movable device, others may provide over current protection for deactivating the motor based on excess current to the electric motor, while others may provide various combinations of features.
One example of such a motor and movable device employing control circuits includes conventional automatic doors. Such doors are implemented in various configurations such as, for example, sliding doors, rotating panel doors, folding doors, and revolving doors. Automatic doors are often relied on for security and fire safety purposes. These automatic door systems often include various sensors and switches to assist in the control of the doors, including detecting obstructions or anomalous operation.
For example, a conventional automatic door, when used as a fire door, may include a switch or actuator in a lead post for detecting an obstruction of the door while the door is closing, which may indicate a person trying to pass by the door when it is closing.
In other automatic doors, the current to a motor controller and/or motor may be monitored for unusual or atypical requirements. Unusual or atypical requirements may indicate an obstruction. To determine what is unusual, some control systems compare a current profile for normal operation to current measurements during operation of a door to identify discrepancies.
If an obstruction is detected, the movable door's operation may be changed or adjusted to respond to the obstruction. Operating according to an obstruction response routine may in turn affect current requirements for the control system and therefore the reliability of obstruction detection that relies on a comparison with a profile based on standard operation.
The prior art may have other disadvantages, limitations, or unaddressed needs.
There is a need, therefore, for a control system that will smoothly operate a door in the event of an obstruction while maintaining its ability to detect and respond to legitimate obstructive events.